To investigate chromatin localization in the nucleus, researchers at the Weizmann Institute of Science used the scripting capability of Arivis Vision4D to implement a customized python script into their image-processing workflow. They managed to split the nucleus into multiple concentric radial shells in three dimensions (see Figure 1A), allowing them to precisely measure the fluorescence intensity in the different shells independently and export it to MATLAB for further downstream analysis. Their research has been published in Science Advances in June 2021.
Live imaging of chromatin distribution reveals novel principles of nuclear architecture and chromatin compartmentalization
The three-dimensional organization of chromatin contributes to transcriptional control, but information about native chromatin distribution is limited. Imaging chromatin in live Drosophila larvae, with preserved nuclear volume, revealed that active and repressed chromatin separates from the nuclear interior and forms a peripheral layer underneath the nuclear lamina. This is in contrast to the current view that chromatin distributes throughout the nucleus. Furthermore, peripheral chromatin organization was observed in distinct Drosophila tissues, as well as in live human effector T lymphocytes and neutrophils. Lamin A/C up-regulation resulted in chromatin collapse toward the nuclear center and correlated with a significant reduction in the levels of active chromatin. Physical modeling suggests that binding of lamina-associated domains combined with chromatin self-attractive interactions recapitulate the experimental chromatin distribution profiles. Together, our findings reveal a novel mode of mesoscale organization of peripheral chromatin sensitive to lamina composition, which is evolutionary conserved.